There has also been an increase in mumps cases this year, and Public Health Wales is urging young people and their parents to have the two doses of the MMR vaccine to protect themselves against mumps, as well as measles and rubella.

Up to the end of May 2013, there were 76 confirmed cases of mumps in Wales for the year so far – compared with 77 cases for the whole of 2011 and 88 for the whole of 2012.

Around 35,000 in this age group remain unvaccinated and there is concern that this could lead to outbreaks of mumps as well as future measles outbreaks.

Dr Marion Lyons, Director of Health Protection for Public Health Wales, said: “Outbreaks of mumps very often occur in older children and teenagers and there is a very real concern that while we have too few people aged 10 to 18 vaccinated with MMR in Wales, they are at risk of mumps as well as measles.

“Mumps is always circulating in Wales but the number of cases we have seen this year is particularly high. It is important for young people and their parents to be aware that this can be a serious infection.

“Two doses of the MMR vaccine is the only protection against measles, mumps and rubella. Anyone born after 1970 who has not had these infections or been vaccinated should speak to their GP urgently.”

Mumps is a viral infection that is caught from the saliva of an infected person. It causes a headache and fever followed in a few days by painful swelling of the glands in the neck on one or both sides.

It is usually a mild infection but can have severe consequences such as meningitis.

Dr Lyons added: “The first dose of MMR is usually given to babies at 12 months of age and the second at three years and four months of age, but it is never too late to catch up on missed doses.

“The measles outbreak centred on Swansea has slowed significantly, but parents should not believe this is the last we will see of measles in Wales if large numbers remain unvaccinated.

“This outbreak has shown us how quickly infection can spread between people who are not vaccinated. While we have tens of thousands of people between 10 and 18 not vaccinated, who continue to mix with one another at school and at social events, we can’t rule out another large outbreak of measles or mumps in the coming months or years.

“The message remains that these infections can be extremely serious and anyone not fully vaccinated is at risk. If you are not vaccinated, now is the time to contact your GP.”